When a barcode symbol is included within a document containing other information, there are two problems. The first is how to identify the barcode location. The second problem relates to reading the thus located barcode data. The present invention addresses only the first problem, and is mainly concerned with how to distinguish the barcode from other markings such as printed matter on the document.
One prior technique for locating and reading a barcode is disclosed in Sarna et al, U.S. Pat. No. 4,873,426 where scanning is in a direction generally perpendicular to the orientation of the code bars. Such scanning is on a row-by-row basis to identify rows above and below an identified row that matches certain stored parameters. The row most likely to contain a barcode is read. Only a single barcode can be identified on a document page.
Another prior technique for determining barcode location is disclosed in commonly owned co-pending Lee et al, U.S. Patent Application Ser. No. 07/289,662 filed Dec. 22, 1988, now U.S. Pat. No. 4,948,955. The techniques there disclosed locate the barcode at any position or direction using an initial down-sampling to a coarse resolution thereby to reduce the time required for location determination at a sacrifice of image resolution.